The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
A continuously variable transmission (“CVT”) typically includes gearing that operatively couples a variator between a rotary power source, such as an engine or electric motor, and a final drive unit. The variator includes a rotary input disk and a rotary output disk which are able to steplessly or continuously vary the ratio of an input speed to an output speed (the “variator ratio”). The overall speed ratio provided by the CVT is a function of the variator ratio and the associated gearing. The output disc may include integrally formed gear teeth that are in mesh with and drive a corresponding gear. The gear in turn is functionally coupled to an output shaft or layshaft that is functionally coupled to the final drive unit.
Some CVTs use bipolar stepper motors for variator ratio control. These stepper motors require complex control to drive each winding in two directions, which typically involves using an H-bridge driver for each winding. Accordingly, a system designer needs to find packaging space for four H-bridge drivers, but designers are constantly looking to reduce the need for extra space.